In sum, Pyongyang has launched seven projectiles into the Sea of Japan since Friday March 18.

The missile launches have corresponded with massive, joint South Korean-U.S. military exercises in South Korea. North Korea has loudly protested the maneuvers and have suggested they are an act of provocation.

Since mid-February, Pyongyang has threatened nuclear attacks on the United States and South Korea and has announced the hermit kingdom expected to test a nuclear missile in the near future.

Such a test would be a violation of United Nations (UN) resolutions.

Washington has responded with stiffer sanctions and the UN recently expanded its sanctions to include restrictions on the importation of small arms and light weapons.